扁平超大断面隧道的施工力学特征及其动力稳定性分析  

Construction Mechanics of Tunnel with Super-Large CrossSection and Its Dynamic Stability

作　　者：施有志[1,2] 李建锋 李汪颖 周先齐[1] 

机构地区：[1]厦门理工学院土木工程与建筑学院,福建厦门361021 [2]上海交通大学船舶海洋与建筑工程学院,上海200240 [3]平潭综合实验区交通与建设工程质量安全监督站,福建平潭350400 [4]西安交通大学航空航天学院,西安710049

出　　处：《上海交通大学学报》2015年第7期1023-1029,共7页Journal of Shanghai Jiaotong University

基　　金：厦门理工学院高层次人才科技类项目(YKJ14011R)

摘　　要：针对超大断面小近距隧道支护设计中的围岩压力分布、位移变形特征问题,以牛寨山双洞八车道公路隧道为研究对象,建立了考虑工程实际地形、工程地质的三维有限元模型,开展了隧道开挖的施工力学形态数值模拟分析,得到了隧道施工过程中隧道围岩变形规律,探讨了小净距大断面隧道近接施工的影响规律.结果表明,小净距大断面隧道所表现出来的施工力学特性复杂,由于偏压的影响,围岩整体水平位移呈非对称分布,最大水平位移发生在南线隧道拱肩处,隧道拱顶下沉最大值发生在先行洞,隧道仰拱处隆起较大;应力集中在两洞仰拱和拱脚处.在此基础上,开展了隧道开挖后的动力有限元计算,分析了洞口段地震力作用下的动力响应,评价了其动力稳定性.计算结果可为优化设计、指导隧道施工以及为隧道稳定性和支护结构安全性评价提供参考.The force of closely-spaced tunnel with super-large cross-section changes a lot because the flat rate becomes smaller. Aimed at the problem of displacement deformation characteristics and the pressure distribution of the surrounding rock in closely-spaced tunnel supporting design with super-large cross-sec- tion, and baseid on the two-hole eight-lane highway tunnel in Niu Zhai Hill, this paper established a three- dimensional finite element model considering the actual terrain and geology. It conducted a numerical simu- lation analysis of the construction mechanical form of the tunnel under excavation, obtained the law of tun- nel surrounding rock deformation during tunnel cons, and investigated the influencing law of proximity construction for closely-spaced large-section tunnel. The results show that the construction mechanical properties o{ closely-spaced large-section tunnel are complex. Due to the influence of bias pressure, the overall horizontal displacement of the surrounding rock is unsymmetrical distributed~ the maximum hori zontal displacement occurs in the spandrel of south-line tunnel, the maximum subsidence of tunnel vault occurs in first hole, and the bulge at the tunnel invert is large. The stress concentrates in the invert and arch foot of the two holes. Based on these findings and considering the earthquake damage of tunnel en- trance easily caused by bias pressure and ultra-shallow cover, this paper performed dynamic finite element calculation after tunneling, analyzed the dynamic response under earthquake force of portal section, and e valuated its dynamic stability. The results provide basis for the optimal design, tunnel construction guid- ance and evaluation of tunnel stability and safety o{ supporting structure.

关 键 词：超大断面小近距隧道 施工力学 围岩应力 支护设计 动力响应 

分 类 号：U452[建筑科学—桥梁与隧道工程]